A semiconductor process device includes a chamber housing defining an internal region and a plurality of electrostatic chucks within the internal region. The chamber housing includes a window, and a light collection unit including a first optical system and a second optical system located at different positions on the window. A plurality of first optical pickup units are connected to the first optical system, and a plurality of second optical pickup units are connected to the second optical system. A sensor includes a plurality of photodetectors that are configured to convert a first optical signal transmitted by the plurality of first optical pickup units and a second optical signal transmitted by the plurality of second optical pickup units into electrical signals. A processor is configured to generate a spatial image of the internal region of the chamber housing using the electrical signals output by the plurality of photodetectors, and determine a location at which an arc occurs in the internal region of the chamber housing based on the spatial image.